In order to obtain larger quantities of a silver halide emulsion having excellent properties as manufactured in a small scale reaction apparatus used for experimental research (usually form 1 to 5 liters in capacity), it is necessary to increase the production scale for the silver halide emulsion to a middle volume (usually, producing in a reaction vessel of from 10 to 150 liters). If the emulsion having the desired performance can be produced in the reaction vessel of the middle volume, it is necessary to increase then the production scale of the emulsion to a large volume (usually form 200 to 2,000 liters). When a silver halide emulsion is produced according to a same production procedure, the performance of the silver halide emulsion produced in a reaction apparatus of the small volume frequently coincides with the performance of the silver halide emulsion produced in a reaction apparatus of the middle volume but does not frequently coincide with the performance of the silver halide emulsion produced in a reaction vessel of the large volume.
Accordingly, in the instance of mass-production, the production procedure for the silver halide emulsion is frequently corrected to the extent necessary to make the properties of the silver halide emulsion in a large scale production coincide with the properties obtained in small scale production. However, such corrective efforts are expensive and time-consuming.
The reason is that a silver halide emulsion is conventionally produced by the following method.
That is, (1) the nucleation, (ripening), and the crystal growth are carried out in a same reaction vessel. Hitherto, the production of silver halide emulsions is mainly carried out by the aforesaid method. In this case, there is a case of producing the silver halide emulsion through a ripening step and without passing through a ripening step.
(2) A system of after carrying out the seed crystal formation, placing a part of the seed crystals in a reaction vessel to perform the crystal growth. For example, in Example 1 of U.S. Pat. No. 4,067,739, seed crystals are formed by the steps of nucleating, ripening, and emulsion washing, and a part of the seed crystals is used for the crystal growth. Also, in Examples 7 to 11 of U.S. Pat. No. 4,797,354, after nucleation, using a part thereof, a silver halide emulsion is produced through the steps of ripening and crystal growth. However, in each case, the production of the silver halide emulsion is carried out in a reaction vessel of a same volume level and the nucleation step and the crystal growth step are not carried out in different reaction vessels each having a different volume. Also, in the aforesaid systems, a part of the nucleated emulsion or the seed crystal formed emulsion is utilized.
Also, the problem in a reaction apparatus of a large volume is mainly in that an aqueous silver salt solution and an aqueous halide solution are added as thick bundles of stream but the countermeasure for the problem are not employed.